It would be helpful to have an option for clef changes within an exercise. Cello music is often in bass clef then sometimes switches to tenor for high notes or treble for really high notes in the middle of the song. Attached is a selection from Brahms Op. 38 as an example. The clef transitions can be anywhere. Note how the transition into measure 30 is hinted at in the end of measure 29. The clef transitions can even occur mid measure. For example, in measure 26 the measure starts in bass clef then last eighth note switches to tenor clef.
This applies to piano music too (though tenor clef isn't involved). For piano we see sometimes both hands in bass clef or both hands in treble clef.
Thanks for a great tool,